This invention relates to a process for producing a free-machining, high sulfur steel alloy.
As is known, the so-called free-machining carbon steel alloys which do not contain lead are classified as either the 1200 Series grades or the 1100 Series grades. Steels of this type typically contain no more than about 0.35% sulfur and at least 0.30% manganese which forms, with the sulfur, manganese sulfide particles which act to improve machinability.
In the past, most alloys of this type have been formed by initial casting into ingots, the resulting ingots being processed in a blooming mill into billets which are subsequently rolled into desired shapes such as bars. When sulfur-containing steels are formed in this manner, this sulfur content cannot be increased above about 0.35% for the reason that sulfur above this limit forms iron sulfide, regardless of the amount of manganese added, which severely reduces the hot-workability of the steel to the point where it cannot be successfully hot-rolled. Nevertheless, higher amounts of manganese sulfide in the microstructure would further improve machinability of the alloy.